Topological disorder an amorphous semiconductors: a real-space renormalisation for Husimi cacti alloys

Decimation techniques have already been used successfully to describe the densities of states of several types of disordered linear chains. In this paper the decimation procedure is extended for the case of Husimi cacti. These lattices are widely used as approximations to the continuous-random-network model for an ideal amorphous tetrahedral bonded semiconductor. The densities of states for disordered Husimi cacti for different concentrations of sixfold and fivefold rings are calculated. The effects of the presence of odd rings on the densities of states and in particular on the band edges are discussed.